Hard alloy welding powder for valve sealing surface surfacing and preparation method of hard alloy welding powder

Abstract

The invention discloses hard alloy welding powder for valve sealing surface surfacing and a preparation method of the hard alloy welding powder. The welding powder comprises 1.20%-1.40% of C element, 2.70%-3.5% of Si element, 3.00%-4.50% of Mn element, 24.00%-26.00% of Cr element, 2.00%-2.20% of Mo element, 3.50%-4.50% of Ni element, smaller than or equal to 0.20% of Co element, smaller than or equal to 0.02% of B element, smaller than or equal to 0.10% of N element and the balance Fe element. The preparation method comprises the following steps: weighing raw materials, mixing and smelting the raw materials to obtain alloy liquid; and the alloy liquid is subjected to gas atomization to prepare powder, and the hard alloy welding powder is obtained after screening. The Co element content is strictly limited, and meanwhile the hardness and other performance can meet the design requirement; the preparation method is simple and reliable in process.

Description

Technical Field

[0001] The present application belongs to the field of welding technology, and relates to a welding powder and a preparation method thereof, and in particular to a cemented carbide welding powder for surfacing welding of valve sealing surfaces and a preparation method thereof. Background Art

[0002] At present, the sealing surface of nuclear power valves uses special welding materials, and the most mature application is the cobalt-based Stellite alloy (Stellite) cladding material. Among them, ERCoCr-A (American Standard System, AWS A5.21) is the most widely used. Specific parameters are shown in the table below:

[0003] Table 1 ERCoCr-A element mass fraction

[0004]

[0005] The sealing surface of the cobalt-based Stellite alloy valve is subject to wear and corrosion during use, and a small amount of cobalt-based alloy debris will enter the primary circuit medium. These cobalt elements (59Co, stable isotope) will be transformed into the strong radioactive isotope 60Co after neutron irradiation as the medium flows through the core, becoming the main radiation source. The cobalt content of the cladding sealing surface of the nuclear island valve accounts for about 60-70% of the total cobalt content of the primary circuit equipment. Therefore, the cobalt-based alloy material of the nuclear island valve sealing surface has become the factor with the greatest impact on the occupational radiation dose level of nuclear power plant operation and maintenance personnel. Summary of the invention

[0006] The technical problem to be solved by the present application is to provide a cemented carbide welding powder with strictly limited Co element content and hardness and other properties that can meet the design requirements in view of the above-mentioned defects of the prior art.

[0007] The technical problem to be further solved by the present application is to provide a preparation method which is simple in process and reliable.

[0008] The technical solution adopted by this application to solve its technical problem is:

[0009] A hard alloy welding powder for surfacing welding of valve sealing surfaces is constructed, comprising the following components by weight: 1.20-1.40% of C element, 2.70-3.5% of Si element, 3.00-4.50% of Mn element, 24.00-26.00% of Cr element, 2.00-2.20% of Mo element, 3.50-4.50% of Ni element, ≤0.20% of Co element, ≤0.02% of B element, ≤0.10% of N element, and the balance of Fe element.

[0010] Furthermore, the cemented carbide welding powder for surfacing the valve sealing surface preferably includes the following components in percentage by weight: 1.30-1.35% C element, 2.70-3.10% Si element, 3.10-3.50% Mn element, 24.00-25.00% Cr element, 2.05-2.15% Mo element, 3.80-4.40% Ni element, ≤0.20% Co element, ≤0.015% B element, ≤0.06% N element, and the balance is Fe element.

[0011] Furthermore, the cemented carbide welding powder used for surfacing welding of the valve sealing surface preferably includes the following components in percentage by weight: 1.32% of C element, 2.75% of Si element, 3.19% of Mn element, 24.37% of Cr element, 2.06% of Mo element, 3.87% of Ni element, ≤0.20% of Co element, ≤0.011% of B element, ≤0.06% of N element, and the balance is Fe element.

[0012] A method for preparing cemented carbide welding powder for surfacing welding of valve sealing surfaces comprises the following steps:

[0013] S1. Weighing materials: single crystal silicon, electrolytic manganese, pure metal chromium, pure metal nickel, pure metal molybdenum and pure metal iron are used as raw materials;

[0014] S2, smelting: mixing and smelting the raw materials obtained in step S1 to obtain a liquid alloy with qualified chemical composition, and then proceeding to step S3;

[0015] S3, atomization: atomizing the alloy liquid obtained in step S2 and meeting the requirements of each element composition of the welding powder to obtain mixed powders of different finenesses;

[0016] S4, sieving: sieving the mixed powder obtained in step S3 to obtain welding powder of a specified mesh size.

[0017] Furthermore, in the method for preparing the cemented carbide welding powder, preferably in the step S1, the amount of the raw materials is calculated according to the mass percentage of the following elements: Si element 2.70-3.5%, Mn element 3.00-4.50%, Cr element 24.00-26.00%, Mo element 2.00-2.20%, Ni element 3.50-4.50%, and the balance is Fe element.

[0018] Furthermore, in the method for preparing the cemented carbide welding powder, preferably in the step S2, the smelting is performed using a medium frequency furnace or an AOD refining furnace, the smelting temperature is controlled at 1400-1500° C., and the temperature is maintained for 30-40 minutes.

[0019] Furthermore, in the method for preparing the cemented carbide welding powder, preferably in the step S2, an alloy liquid is obtained after smelting, and the chemical composition of the alloy liquid is tested. If it meets the requirements of the elements of the welding powder and the chemical composition is qualified, then the step S3 is entered. If not, raw materials are added in the same proportion, and the smelting is performed again. The chemical composition of the alloy liquid is tested again. If not, the raw materials are added in the same proportion and the smelting is repeated until the chemical composition is qualified.

[0020] Furthermore, in the method for preparing cemented carbide welding powder, preferably in step S3, the atomization is: using ultra-low temperature atomization medium to flush the molten liquid to directly form powder.

[0021] Furthermore, in the method for preparing cemented carbide welding powder, preferably in step S3, the ultra-low temperature atomization medium is: ultra-low temperature nitrogen, helium or argon.

[0022] Furthermore, in the method for preparing cemented carbide welding powder, preferably in step S4, the prescribed mesh size is 100 to 270 meshes.

[0023] The implementation of this application has the following beneficial effects:

[0024] The cemented carbide welding powder of this application is a welding powder specially used for surfacing welding on the valve sealing surface. The Co element content is strictly limited, and its Co element content is ≤0.20%, which is much lower than the 60-70% content of the prior art. When the debris and corrosion products generated by the wear and corrosion of the alloy valve sealing surface during use enter the primary circuit medium, the very low content of Co element will not form a radiation source, avoiding the resulting impact on the occupational radiation dose level of nuclear power plant operation and maintenance personnel. At the same time, it complies with the clear provisions of the equipment technical specifications for valves in the new technical specifications, namely, the requirement that "for valves with reactor coolant as the medium, the cemented carbide surface materials of the valve seat and valve disc are recommended to use cobalt-free alloys. In non-radioactive systems, the cemented carbide surfaces of the valve seat and valve disc can use cobalt-based alloys". In addition, in addition to strictly controlling the cobalt element content, the welding powder of this application, other technical indicators such as hardness and welding quality meet the welding requirements.

[0025] The preparation method of the present application adopts various metal raw materials, and after the raw materials are uniformly mixed, they are smelted into alloy liquid, and then atomized into mixed powder, and sieved to obtain welding powder of a specified mesh size. The whole preparation process is simple, reliable and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solution of the present application, the present application will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the following drawings only show certain embodiments of the present application and should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work. In the drawings:

[0027] Figure 1 It is a surfacing pattern of the surfacing test of the embodiment of the present application;

[0028] Figure 2 Schematic diagram of the test position of the cladding test in the embodiment of the present application;

[0029] Figure 3 This is the macroscopic metallographic image of the weld in Example 1 of the present application;

[0030] Figure 4 This is the macroscopic metallographic image of the weld in Example 2 of the present application;

[0031] Figure 5 This is the macroscopic metallographic image of the weld in Example 3 of the present application. DETAILED DESCRIPTION

[0032] In order to have a clearer understanding of the technical features, purposes and effects of the present application, the specific implementation methods of the present application are now described in detail with reference to the accompanying drawings.

[0033] In the following description, some specific details are provided for the purpose of explanation rather than limitation so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application can also be implemented in other embodiments without these specific details.

[0034] The cemented carbide welding powder of this application is a welding powder specially used for surfacing welding of valve sealing surfaces. It must not only meet the technical requirements of conventional welding powder, but also meet the special requirements related to nuclear power. Therefore, in view of the problems existing in the cobalt-based Stellite surfacing materials of the prior art, the Co element content is strictly limited to make its Co element content ≤0.20%. The specific welding powder technical solution is as follows:

[0035] A hard alloy welding powder for surfacing welding of valve sealing surfaces comprises the following components by weight: 1.20-1.40% of C element, 2.70-3.5% of Si element, 3.00-4.50% of Mn element, 24.00-26.00% of Cr element, 2.00-2.20% of Mo element, 3.50-4.50% of Ni element, ≤0.20% of Co element, ≤0.02% of B element, ≤0.10% of N element, and the balance of Fe element.

[0036] In the above welding powder components, the content of Co element is ≤0.20%, which is much lower than the 60-70% content in the prior art. When the valve is used, if wear and corrosion occur, when the debris and corrosion products enter the primary circuit medium, since the content of Co element in the debris and corrosion products is very low, no radiation source will be formed, thus avoiding the impact on the occupational radiation dose level of nuclear power plant operation and maintenance personnel. In addition, in addition to strictly controlling the content of cobalt element, the other technical indicators of the welding powder of this application are implemented in accordance with Table 2 of the standard RCC-MS8000 (2007 edition).

[0037] Specifically, the present application preferably includes the following components in percentage by weight: C element 1.30-1.35%, Si element 2.70-3.10%, Mn element 3.10-3.50%, Cr element 24.00-25.00%, Mo element 2.05-2.15%, Ni element 3.80-4.40%, Co element ≤0.20%, B element ≤0.015%, N element ≤0.06%, and the balance is Fe element.

[0038] The most preferred components include the following mass percentages: C element 1.32%, Si element 2.75%, Mn element 3.19%, Cr element 24.37%, Mo element 2.06%, Ni element 3.87%, Co element ≤0.20%, B element ≤0.011%, N element ≤0.06%, and the balance is Fe element.

[0039] A method for preparing cemented carbide welding powder for surfacing welding of valve sealing surfaces comprises the following steps:

[0040] S1. Weighing materials: single crystal silicon, electrolytic manganese, pure metal chromium, pure metal nickel, pure metal molybdenum and pure metal iron are used as raw materials; the amount of the raw materials is calculated according to the mass percentage of the following elements: Si element 2.70-3.5%, Mn element 3.00-4.50%, Cr element 24.00-26.00%, Mo element 2.00-2.20%, Ni element 3.50-4.50%, and the balance is Fe element. Among the above element components, Fe element, Si element, Mn element, Cr element, Mo element, and Ni element are the main components, and the rest are impurity components, which are brought by the raw materials of the main components.

[0041] Preferably, the amount of the raw materials is calculated according to the mass percentage of the following elements: Si element 2.70-3.10%, Mn element 3.10-3.50%, Cr element 24.00-25.00%, Mo element 2.05-2.15%, Ni element 3.80-4.40%, and the balance is Fe element.

[0042] The most preferred amount of the raw materials is calculated according to the mass percentage of the following elements: 2.75% Si element, 3.19% Mn element, 24.37% Cr element, 2.06% Mo element, 3.87% Ni element, and the balance is Fe element.

[0043] S2, smelting: the raw materials obtained in step S1 are mixed and smelted to obtain a liquid alloy with qualified chemical composition, and then the process proceeds to step S3; specifically, after smelting, the liquid alloy is obtained, and the chemical composition of the liquid alloy is tested. If it meets the requirements of each element composition of the welding powder, the chemical composition is qualified, then the process proceeds to step S3. If not, raw materials are added in the same proportion, and the process is smelted again. The chemical composition of the liquid alloy is tested again. If not, the process repeats the addition of raw materials in the same proportion and smelting until the chemical composition is qualified.

[0044] Specifically, the smelting is carried out in a medium frequency furnace or an AOD refining furnace, the smelting temperature is controlled at 1400-1500°C, and the temperature is maintained for 30-40 minutes. Any value within the smelting temperature range meets the requirements of the present application, for example, the smelting temperature can be controlled at 1400°C, 1420°C, 1450°C, 1470°C, 1490°C, 1500°C to achieve the present invention, and the temperature is maintained within the above range to meet the requirements of the present application, for example, maintaining for 30, 32, 35, 38, 40 minutes to achieve the present invention.

[0045] In this step, since the raw materials are proportioned according to the element ratio, they basically meet the requirements of the welding powder composition. However, due to the small amount of impurities in the raw materials, such as Co, B, N, and C, the content in the raw materials is relatively high, or they are superimposed after mixing, so that these impurities exceed the requirements of the welding powder composition ratio, it is necessary to increase various raw materials in the same proportion and continue to smelt until the chemical composition is qualified. This application not only maintains the welding powder composition ratio, but also reduces the proportion of impurities. Only after passing the test can we proceed to the next step.

[0046] S3, atomization: atomize the alloy liquid obtained in step S2 that meets the requirements of each element composition of the welding powder to obtain mixed powders of different finenesses; specifically, the atomization is: using ultra-low temperature atomization medium to flush the molten liquid to directly form powder. The ultra-low temperature atomization medium is: ultra-low temperature nitrogen, helium or argon. The above three ultra-low temperature atomization media are all applicable to this application and can be gasified using existing liquid media. Preferably, gasified liquid nitrogen at -196°C is used.

[0047] S4, sieving: sieving the mixed powder obtained in step S3 to obtain welding powder of a specified mesh size, wherein the specified mesh size is 100 to 270 meshes.

[0048] The present application is described in detail through the following specific embodiments:

[0049] Embodiment 1: A cemented carbide welding powder for surfacing welding of valve sealing surfaces, comprising the following components by weight:

[0050]

[0051] Preparation method: S1. Weighing raw materials: weighing raw materials single crystal silicon, electrolytic manganese, pure metallic chromium, pure metallic nickel, pure metallic molybdenum and pure metallic iron; the amount of the raw materials is calculated according to the mass percentage of Fe element, Si element, Mn element, Cr element, Mo element and Ni element in the above table, that is, the content of each element in the table is converted into the amount of various raw materials for weighing.

[0052] S2, smelting: the raw materials obtained in step S1 are mixed, smelted in a medium frequency furnace, the smelting temperature is controlled at 1420°C, the temperature is maintained for 30 minutes, and the alloy liquid is obtained by smelting, and the chemical composition of the alloy liquid is tested to meet the requirements of each element composition of the welding powder in the above table. The method for testing the chemical composition is a conventional technology and will not be repeated here.

[0053] S3, atomization: the alloy liquid obtained in the step S2 is atomized by flushing the molten liquid with vaporized liquid nitrogen at -196°C to form powder, thereby obtaining mixed powders of different finenesses;

[0054] S4, sieving: The mixed powder obtained in step S3 is sifted through a powder sieving machine to obtain a cemented carbide welding powder with a fineness of 150 meshes. The fineness of 100 meshes mentioned here means that the fineness of most particles in the powder is 150 meshes, and the same applies below.

[0055] Embodiment 2: A cemented carbide welding powder for surfacing welding of valve sealing surfaces, comprising the following components by weight:

[0056]

[0057] Preparation method: S1. Weighing raw materials: weighing raw materials single crystal silicon, electrolytic manganese, pure metallic chromium, pure metallic nickel, pure metallic molybdenum and pure metallic iron; the amount of the raw materials is calculated according to the mass percentage of Fe element, Si element, Mn element, Cr element, Mo element and Ni element in the above table, that is, the content of each element in the table is converted into the amount of various raw materials for weighing.

[0058] S2, smelting: the raw materials obtained in step S1 are mixed, and smelted in a medium frequency furnace, the smelting temperature is controlled at 1400°C, the temperature is maintained for 40 minutes, and the alloy liquid is obtained by smelting, and the chemical composition of the alloy liquid is tested to meet the requirements of each element composition of the welding powder in the above table. The method for testing the chemical composition is a conventional technology and will not be repeated here.

[0059] S3, atomization: the alloy liquid obtained in the step S2 is atomized by flushing the molten liquid with vaporized liquid nitrogen at -196°C to form powder, thereby obtaining mixed powders of different finenesses;

[0060] S4, sieving: the mixed powder obtained in step S3 is sifted through a powder sifter to obtain cemented carbide welding powder with a fineness of 270 mesh.

[0061] Embodiment 3: A cemented carbide welding powder for surfacing welding of valve sealing surfaces, comprising the following components by weight:

[0062]

[0063] Preparation method: S1. Weighing raw materials: weighing raw materials single crystal silicon, electrolytic manganese, pure metallic chromium, pure metallic nickel, pure metallic molybdenum and pure metallic iron; the amount of the raw materials is calculated according to the mass percentage of Fe element, Si element, Mn element, Cr element, Mo element and Ni element in the above table, that is, the content of each element in the table is converted into the amount of various raw materials for weighing.

[0064] S2, smelting: the raw materials obtained in step S1 are mixed, smelted in a medium frequency furnace, the smelting temperature is controlled at 1500°C, the temperature is maintained for 35 minutes, and the alloy liquid is obtained by smelting, and the chemical composition of the alloy liquid is tested to meet the requirements of each element composition of the welding powder in the above table. The method for testing the chemical composition is a conventional technology and will not be repeated here.

[0065] S3, atomization: the alloy liquid obtained in the step S2 is atomized by flushing the molten liquid with vaporized liquid nitrogen at -196°C to form powder, thereby obtaining mixed powders of different finenesses;

[0066] S4, sieving: the mixed powder obtained in step S3 is sifted through a powder sifter to obtain cemented carbide welding powder with a fineness of 200 mesh.

[0067] Embodiment 4: A cemented carbide welding powder for surfacing welding of valve sealing surfaces, comprising the following components by weight:

[0068]

[0069] Preparation method: S1. Weighing raw materials: weighing raw materials single crystal silicon, electrolytic manganese, pure metallic chromium, pure metallic nickel, pure metallic molybdenum and pure metallic iron; the amount of the raw materials is calculated according to the mass percentage of Fe element, Si element, Mn element, Cr element, Mo element and Ni element in the above table, that is, the content of each element in the table is converted into the amount of various raw materials for weighing.

[0070] S2, smelting: the raw materials obtained in step S1 are mixed, and smelted in an AOD refining furnace, the smelting temperature is controlled at 1450°C, the temperature is maintained for 37 minutes, and the alloy liquid is obtained by smelting, and the chemical composition of the alloy liquid is tested, and it meets the requirements of each element composition of the welding powder in the above table. The method for testing the chemical composition is a conventional technology and will not be repeated here.

[0071] S3, atomization: the alloy liquid obtained in the step S2 is atomized by flushing the molten liquid with vaporized liquid helium below -100°C to form powder, thereby obtaining mixed powders of different finenesses;

[0072] S4, sieving: the mixed powder obtained in step S3 is sifted through a powder sifter to obtain cemented carbide welding powder with a fineness of 150 mesh.

[0073] Embodiment 5: A cemented carbide welding powder for surfacing welding of valve sealing surfaces, comprising the following components in percentage by weight:

[0074]

[0075] Preparation method: S1. Weighing raw materials: weighing raw materials single crystal silicon, electrolytic manganese, pure metallic chromium, pure metallic nickel, pure metallic molybdenum and pure metallic iron; the amount of the raw materials is calculated according to the mass percentage of Fe element, Si element, Mn element, Cr element, Mo element and Ni element in the above table, that is, the content of each element in the table is converted into the amount of various raw materials for weighing.

[0076] S2, smelting: the raw materials obtained in step S1 are mixed, smelted in a medium frequency furnace, the smelting temperature is controlled at 1420°C, the temperature is maintained for 33 minutes, and the alloy liquid is obtained by smelting, and the chemical composition of the alloy liquid is tested, which meets the requirements of the elements of the welding powder in the above table. The method for testing the chemical composition is a conventional technology and will not be repeated here.

[0077] S3, atomization: the alloy liquid obtained in the step S2 is atomized by flushing the molten liquid with -185.8°C gasified liquid argon to form powder, thereby obtaining mixed powders of different finenesses;

[0078] S4, sieving: the mixed powder obtained in step S3 is sifted through a powder sifter to obtain cemented carbide welding powder with a fineness of 100 mesh.

[0079] Test verification: The quality requirements of the cemented carbide welding powder used for surfacing welding on the valve sealing surface are implemented in accordance with the standard RCC-M S8000. The following is a surfacing test of the welding powder of the present application with reference to the above standard requirements and taking Examples 1-3 as examples:

[0080] PAW plasma welding was used for surfacing test. Figure 1 , Figure 2 The test specimens were manufactured as shown.

[0081] 1. Hardness test: Ten specimens were made from the welding powders of Examples 1 to 3 respectively, and surfacing tests were performed. Hardness tests were performed on the welds, and the average values ​​of the test results were averaged to evaluate the welding powders.

[0082] Hardness test results (HRC)

[0083]

[0084] It can be seen from the table that the weld hardness test results of the welding powder welding of the present application meet the requirements of the RCC-M S8000 standard.

[0085] 2. Wear test: Wear test is carried out on welding material samples, and the wear rate of cobalt-based welding materials of the same grade is compared.

[0086] Comparison of sample wear rate (%)

[0087]

[0088] It can be seen from the table that the wear rates of the three samples of the present application are much lower than those of the existing cobalt-based welding powder at both room temperature and high temperature, and the hardness loss rate at high temperature is better than that of the cobalt-based material of the same grade. The low wear rate not only reduces the amount of welding powder alloy debris entering the primary circuit, but also reduces the total content of cobalt element.

[0089] 3. Welding quality inspection:

[0090] The present application examines the welding quality through macroscopic metallographic photographs of Examples 1-3, and obtains the following: Figure 3-5 The metallographic diagram shown, the specific results are as follows:

[0091] 1) Overall weld: The weld is two-layered and has no cracks, incomplete penetration, incomplete fusion or porosity defects after testing.

[0092] 2) Weld: no micro cracks and precipitation defects.

[0093] 3) Heat affected zone: no micro cracks and precipitation defects.

[0094] 4) Base material: no micro cracks and precipitation defects.

[0095] From the above, it can be seen that the welding quality of this application is excellent.

[0096] It can be understood that the above embodiments only express the preferred implementation methods of the present application, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present application; it should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, the above-mentioned technical features can be freely combined, and several deformations and improvements can be made, which all belong to the protection scope of the present application; therefore, all equivalent changes and modifications made to the scope of the claims of the present application should fall within the scope of the claims of the present application.

Claims

1. A cemented carbide welding powder for surfacing welding of valve sealing surface, characterized in that: The invention comprises the following components in percentage by weight: C element 1.20-1.40%, Si element 2.70-3.50%, Mn element 3.00-4.50%, Cr element 24.00-26.00%, Mo element 2.00-2.20%, Ni element 3.50-4.50%, Co element ≤0.20%, B element ≤0.02%, N element ≤0.10%, and the balance is Fe element.

2. The hard alloy welding powder for surfacing welding of valve sealing surface according to claim 1, characterized in that: The invention comprises the following components in percentage by weight: C element 1.30-1.35%, Si element 2.70-3.10%, Mn element 3.10-3.50%, Cr element 24.00-25.00%, Mo element 2.05-2.15%, Ni element 3.80-4.40%, Co element ≤0.20%, B element ≤0.015%, N element ≤0.06%, and the balance is Fe element.

3. The hard alloy welding powder for surfacing welding of valve sealing surface according to claim 1, characterized in that: The composition includes the following weight percentages: C element 1.32%, Si element 2.75%, Mn element 3.19%, Cr element 24.37%, Mo element 2.06%, Ni element 3.87%, Co element ≤0.20%, B element ≤0.011%, N element ≤0.06%, and the balance is Fe element.

4. A method for preparing cemented carbide welding powder for surfacing welding of valve sealing surfaces, characterized in that: The following steps are involved: S1. Weighing materials: single crystal silicon, electrolytic manganese, pure metal chromium, pure metal nickel, pure metal molybdenum and pure metal iron are used as raw materials; S2, smelting: mixing and smelting the raw materials obtained in step S1 to obtain a liquid alloy with qualified chemical composition, and then proceeding to step S3; S3, atomization: atomizing the alloy liquid obtained in step S2 and meeting the requirements of each element composition of the welding powder to obtain mixed powders of different finenesses; S4, sieving: sieving the mixed powder obtained in step S3 to obtain welding powder of a specified mesh size.

5. The method for preparing cemented carbide welding powder according to claim 4, characterized in that: In the step S1, the mass ratio of the raw materials is calculated according to the mass percentage of the following elements: Si element 2.70-3.5%, Mn element 3.00-4.50%, Cr element 24.00-26.00%, Mo element 2.00-2.20%, Ni element 3.50-4.50%, and the balance is Fe element.

6. The method for preparing cemented carbide welding powder according to claim 4, characterized in that: In the step S2, the smelting is carried out in a medium frequency furnace or an AOD refining furnace, the smelting temperature is controlled at 1400-1500°C, and the temperature is maintained for 30-40 minutes.

7. The method for preparing cemented carbide welding powder according to claim 4, characterized in that: In the step S2, the alloy liquid is obtained after smelting, and the chemical composition of the alloy liquid is tested. If it meets the requirements of the elements of the welding powder, the chemical composition is qualified, then the step S3 is entered. If not, raw materials are added in the same proportion, and the smelting is performed again. The chemical composition of the alloy liquid is tested again. If not, the raw materials are added in the same proportion and the smelting is repeated until the chemical composition is qualified.

8. The method for preparing cemented carbide welding powder according to claim 4, characterized in that: In the step S3, the aerosolization is: using an ultra-low temperature aerosolization medium to flush the molten liquid to directly form powder.

9. The method for preparing cemented carbide welding powder according to claim 8, characterized in that: In step S3, the ultra-low temperature atomization medium is ultra-low temperature nitrogen, helium or argon.

10. The method for preparing cemented carbide welding powder according to claim 4, characterized in that: In the step S4, the prescribed mesh size is 100 to 270 meshes.

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